// SPDX-License-Identifier: LGPL-2.1
/*
 * Copyright IBM Corporation, 2007
 * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
 *
 */

#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "ext4_extents.h"

/*
 * The contiguous blocks details which can be
 * represented by a single extent
 */
struct migrate_struct {
        ext4_lblk_t first_block, last_block, curr_block;
        ext4_fsblk_t first_pblock, last_pblock;
};

static int finish_range(handle_t *handle, struct inode *inode,
                                struct migrate_struct *lb)

{
        int retval = 0, needed;
        struct ext4_extent newext;
        struct ext4_ext_path *path;
        if (lb->first_pblock == 0)
                return 0;

        /* Add the extent to temp inode*/
        newext.ee_block = cpu_to_le32(lb->first_block);
        newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
        ext4_ext_store_pblock(&newext, lb->first_pblock);
        /* Locking only for convenience since we are operating on temp inode */
        down_write(&EXT4_I(inode)->i_data_sem);
        path = ext4_find_extent(inode, lb->first_block, NULL, 0);
        if (IS_ERR(path)) {
                retval = PTR_ERR(path);
                goto err_out;
        }

        /*
         * Calculate the credit needed to inserting this extent
         * Since we are doing this in loop we may accumulate extra
         * credit. But below we try to not accumulate too much
         * of them by restarting the journal.
         */
        needed = ext4_ext_calc_credits_for_single_extent(inode,
                    lb->last_block - lb->first_block + 1, path);

        retval = ext4_datasem_ensure_credits(handle, inode, needed, needed, 0);
        if (retval < 0)
                goto err_out;
        path = ext4_ext_insert_extent(handle, inode, path, &newext, 0);
        if (IS_ERR(path))
                retval = PTR_ERR(path);
err_out:
        up_write((&EXT4_I(inode)->i_data_sem));
        ext4_free_ext_path(path);
        lb->first_pblock = 0;
        return retval;
}

static int update_extent_range(handle_t *handle, struct inode *inode,
                               ext4_fsblk_t pblock, struct migrate_struct *lb)
{
        int retval;
        /*
         * See if we can add on to the existing range (if it exists)
         */
        if (lb->first_pblock &&
                (lb->last_pblock+1 == pblock) &&
                (lb->last_block+1 == lb->curr_block)) {
                lb->last_pblock = pblock;
                lb->last_block = lb->curr_block;
                lb->curr_block++;
                return 0;
        }
        /*
         * Start a new range.
         */
        retval = finish_range(handle, inode, lb);
        lb->first_pblock = lb->last_pblock = pblock;
        lb->first_block = lb->last_block = lb->curr_block;
        lb->curr_block++;
        return retval;
}

static int update_ind_extent_range(handle_t *handle, struct inode *inode,
                                   ext4_fsblk_t pblock,
                                   struct migrate_struct *lb)
{
        struct buffer_head *bh;
        __le32 *i_data;
        int i, retval = 0;
        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

        bh = ext4_sb_bread(inode->i_sb, pblock, 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        i_data = (__le32 *)bh->b_data;
        for (i = 0; i < max_entries; i++) {
                if (i_data[i]) {
                        retval = update_extent_range(handle, inode,
                                                le32_to_cpu(i_data[i]), lb);
                        if (retval)
                                break;
                } else {
                        lb->curr_block++;
                }
        }
        put_bh(bh);
        return retval;

}

static int update_dind_extent_range(handle_t *handle, struct inode *inode,
                                    ext4_fsblk_t pblock,
                                    struct migrate_struct *lb)
{
        struct buffer_head *bh;
        __le32 *i_data;
        int i, retval = 0;
        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

        bh = ext4_sb_bread(inode->i_sb, pblock, 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        i_data = (__le32 *)bh->b_data;
        for (i = 0; i < max_entries; i++) {
                if (i_data[i]) {
                        retval = update_ind_extent_range(handle, inode,
                                                le32_to_cpu(i_data[i]), lb);
                        if (retval)
                                break;
                } else {
                        /* Only update the file block number */
                        lb->curr_block += max_entries;
                }
        }
        put_bh(bh);
        return retval;

}

static int update_tind_extent_range(handle_t *handle, struct inode *inode,
                                    ext4_fsblk_t pblock,
                                    struct migrate_struct *lb)
{
        struct buffer_head *bh;
        __le32 *i_data;
        int i, retval = 0;
        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

        bh = ext4_sb_bread(inode->i_sb, pblock, 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        i_data = (__le32 *)bh->b_data;
        for (i = 0; i < max_entries; i++) {
                if (i_data[i]) {
                        retval = update_dind_extent_range(handle, inode,
                                                le32_to_cpu(i_data[i]), lb);
                        if (retval)
                                break;
                } else {
                        /* Only update the file block number */
                        lb->curr_block += max_entries * max_entries;
                }
        }
        put_bh(bh);
        return retval;

}

static int free_dind_blocks(handle_t *handle,
                                struct inode *inode, __le32 i_data)
{
        int i;
        __le32 *tmp_idata;
        struct buffer_head *bh;
        struct super_block *sb = inode->i_sb;
        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
        int err;

        bh = ext4_sb_bread(sb, le32_to_cpu(i_data), 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        tmp_idata = (__le32 *)bh->b_data;
        for (i = 0; i < max_entries; i++) {
                if (tmp_idata[i]) {
                        err = ext4_journal_ensure_credits(handle,
                                EXT4_RESERVE_TRANS_BLOCKS,
                                ext4_free_metadata_revoke_credits(sb, 1));
                        if (err < 0) {
                                put_bh(bh);
                                return err;
                        }
                        ext4_free_blocks(handle, inode, NULL,
                                         le32_to_cpu(tmp_idata[i]), 1,
                                         EXT4_FREE_BLOCKS_METADATA |
                                         EXT4_FREE_BLOCKS_FORGET);
                }
        }
        put_bh(bh);
        err = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
                                ext4_free_metadata_revoke_credits(sb, 1));
        if (err < 0)
                return err;
        ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
                         EXT4_FREE_BLOCKS_METADATA |
                         EXT4_FREE_BLOCKS_FORGET);
        return 0;
}

static int free_tind_blocks(handle_t *handle,
                                struct inode *inode, __le32 i_data)
{
        int i, retval = 0;
        __le32 *tmp_idata;
        struct buffer_head *bh;
        unsigned long max_entries = inode->i_sb->s_blocksize >> 2;

        bh = ext4_sb_bread(inode->i_sb, le32_to_cpu(i_data), 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        tmp_idata = (__le32 *)bh->b_data;
        for (i = 0; i < max_entries; i++) {
                if (tmp_idata[i]) {
                        retval = free_dind_blocks(handle,
                                        inode, tmp_idata[i]);
                        if (retval) {
                                put_bh(bh);
                                return retval;
                        }
                }
        }
        put_bh(bh);
        retval = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
                        ext4_free_metadata_revoke_credits(inode->i_sb, 1));
        if (retval < 0)
                return retval;
        ext4_free_blocks(handle, inode, NULL, le32_to_cpu(i_data), 1,
                         EXT4_FREE_BLOCKS_METADATA |
                         EXT4_FREE_BLOCKS_FORGET);
        return 0;
}

static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
{
        int retval;

        /* ei->i_data[EXT4_IND_BLOCK] */
        if (i_data[0]) {
                retval = ext4_journal_ensure_credits(handle,
                        EXT4_RESERVE_TRANS_BLOCKS,
                        ext4_free_metadata_revoke_credits(inode->i_sb, 1));
                if (retval < 0)
                        return retval;
                ext4_free_blocks(handle, inode, NULL,
                                le32_to_cpu(i_data[0]), 1,
                                 EXT4_FREE_BLOCKS_METADATA |
                                 EXT4_FREE_BLOCKS_FORGET);
        }

        /* ei->i_data[EXT4_DIND_BLOCK] */
        if (i_data[1]) {
                retval = free_dind_blocks(handle, inode, i_data[1]);
                if (retval)
                        return retval;
        }

        /* ei->i_data[EXT4_TIND_BLOCK] */
        if (i_data[2]) {
                retval = free_tind_blocks(handle, inode, i_data[2]);
                if (retval)
                        return retval;
        }
        return 0;
}

static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
                                                struct inode *tmp_inode)
{
        int retval, retval2 = 0;
        __le32  i_data[3];
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);

        /*
         * One credit accounted for writing the
         * i_data field of the original inode
         */
        retval = ext4_journal_ensure_credits(handle, 1, 0);
        if (retval < 0)
                goto err_out;

        i_data[0] = ei->i_data[EXT4_IND_BLOCK];
        i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
        i_data[2] = ei->i_data[EXT4_TIND_BLOCK];

        down_write(&EXT4_I(inode)->i_data_sem);
        /*
         * if EXT4_STATE_EXT_MIGRATE is cleared a block allocation
         * happened after we started the migrate. We need to
         * fail the migrate
         */
        if (!ext4_test_inode_state(inode, EXT4_STATE_EXT_MIGRATE)) {
                retval = -EAGAIN;
                up_write(&EXT4_I(inode)->i_data_sem);
                goto err_out;
        } else
                ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
        /*
         * We have the extent map build with the tmp inode.
         * Now copy the i_data across
         */
        ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
        memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));

        /*
         * Update i_blocks with the new blocks that got
         * allocated while adding extents for extent index
         * blocks.
         *
         * While converting to extents we need not
         * update the original inode i_blocks for extent blocks
         * via quota APIs. The quota update happened via tmp_inode already.
         */
        spin_lock(&inode->i_lock);
        inode->i_blocks += tmp_inode->i_blocks;
        spin_unlock(&inode->i_lock);
        up_write(&EXT4_I(inode)->i_data_sem);

        /*
         * We mark the inode dirty after, because we decrement the
         * i_blocks when freeing the indirect meta-data blocks
         */
        retval = free_ind_block(handle, inode, i_data);
        retval2 = ext4_mark_inode_dirty(handle, inode);
        if (unlikely(retval2 && !retval))
                retval = retval2;

err_out:
        return retval;
}

static int free_ext_idx(handle_t *handle, struct inode *inode,
                                        struct ext4_extent_idx *ix)
{
        int i, retval = 0;
        ext4_fsblk_t block;
        struct buffer_head *bh;
        struct ext4_extent_header *eh;

        block = ext4_idx_pblock(ix);
        bh = ext4_sb_bread(inode->i_sb, block, 0);
        if (IS_ERR(bh))
                return PTR_ERR(bh);

        eh = (struct ext4_extent_header *)bh->b_data;
        if (eh->eh_depth != 0) {
                ix = EXT_FIRST_INDEX(eh);
                for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
                        retval = free_ext_idx(handle, inode, ix);
                        if (retval) {
                                put_bh(bh);
                                return retval;
                        }
                }
        }
        put_bh(bh);
        retval = ext4_journal_ensure_credits(handle, EXT4_RESERVE_TRANS_BLOCKS,
                        ext4_free_metadata_revoke_credits(inode->i_sb, 1));
        if (retval < 0)
                return retval;
        ext4_free_blocks(handle, inode, NULL, block, 1,
                         EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
        return 0;
}

/*
 * Free the extent meta data blocks only
 */
static int free_ext_block(handle_t *handle, struct inode *inode)
{
        int i, retval = 0;
        struct ext4_inode_info *ei = EXT4_I(inode);
        struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
        struct ext4_extent_idx *ix;
        if (eh->eh_depth == 0)
                /*
                 * No extra blocks allocated for extent meta data
                 */
                return 0;
        ix = EXT_FIRST_INDEX(eh);
        for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
                retval = free_ext_idx(handle, inode, ix);
                if (retval)
                        return retval;
        }
        return retval;
}

int ext4_ext_migrate(struct inode *inode)
{
        handle_t *handle;
        int retval = 0, i;
        __le32 *i_data;
        struct ext4_inode_info *ei;
        struct inode *tmp_inode = NULL;
        struct migrate_struct lb;
        unsigned long max_entries;
        __u32 goal, tmp_csum_seed;
        uid_t owner[2];
        int alloc_ctx;

        /*
         * If the filesystem does not support extents, or the inode
         * already is extent-based, error out.
         */
        if (!ext4_has_feature_extents(inode->i_sb) ||
            ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
            ext4_has_inline_data(inode))
                return -EINVAL;

        if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
                /*
                 * don't migrate fast symlink
                 */
                return retval;

        alloc_ctx = ext4_writepages_down_write(inode->i_sb);

        /*
         * Worst case we can touch the allocation bitmaps and a block
         * group descriptor block.  We do need to worry about
         * credits for modifying the quota inode.
         */
        handle = ext4_journal_start(inode, EXT4_HT_MIGRATE,
                3 + EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb));

        if (IS_ERR(handle)) {
                retval = PTR_ERR(handle);
                goto out_unlock;
        }
        /*
         * This operation rewrites the inode's block mapping layout
         * (indirect to extents) and is not tracked in the fast commit
         * log, so disable fast commits for this transaction.
         */
        ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_MIGRATE, handle);
        goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) *
                EXT4_INODES_PER_GROUP(inode->i_sb)) + 1;
        owner[0] = i_uid_read(inode);
        owner[1] = i_gid_read(inode);
        tmp_inode = ext4_new_inode(handle, d_inode(inode->i_sb->s_root),
                                   S_IFREG, NULL, goal, owner, 0);
        if (IS_ERR(tmp_inode)) {
                retval = PTR_ERR(tmp_inode);
                ext4_journal_stop(handle);
                goto out_unlock;
        }
        /*
         * Use the correct seed for checksum (i.e. the seed from 'inode').  This
         * is so that the metadata blocks will have the correct checksum after
         * the migration.
         */
        ei = EXT4_I(inode);
        tmp_csum_seed = EXT4_I(tmp_inode)->i_csum_seed;
        EXT4_I(tmp_inode)->i_csum_seed = ei->i_csum_seed;
        i_size_write(tmp_inode, i_size_read(inode));
        /*
         * Set the i_nlink to zero so it will be deleted later
         * when we drop inode reference.
         */
        clear_nlink(tmp_inode);

        ext4_ext_tree_init(handle, tmp_inode);
        ext4_journal_stop(handle);

        /*
         * start with one credit accounted for
         * superblock modification.
         *
         * For the tmp_inode we already have committed the
         * transaction that created the inode. Later as and
         * when we add extents we extent the journal
         */
        /*
         * Even though we take i_rwsem we can still cause block
         * allocation via mmap write to holes. If we have allocated
         * new blocks we fail migrate.  New block allocation will
         * clear EXT4_STATE_EXT_MIGRATE flag.  The flag is updated
         * with i_data_sem held to prevent racing with block
         * allocation.
         */
        down_read(&EXT4_I(inode)->i_data_sem);
        ext4_set_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
        up_read((&EXT4_I(inode)->i_data_sem));

        handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
        if (IS_ERR(handle)) {
                retval = PTR_ERR(handle);
                goto out_tmp_inode;
        }

        i_data = ei->i_data;
        memset(&lb, 0, sizeof(lb));

        /* 32 bit block address 4 bytes */
        max_entries = inode->i_sb->s_blocksize >> 2;
        for (i = 0; i < EXT4_NDIR_BLOCKS; i++) {
                if (i_data[i]) {
                        retval = update_extent_range(handle, tmp_inode,
                                                le32_to_cpu(i_data[i]), &lb);
                        if (retval)
                                goto err_out;
                } else
                        lb.curr_block++;
        }
        if (i_data[EXT4_IND_BLOCK]) {
                retval = update_ind_extent_range(handle, tmp_inode,
                                le32_to_cpu(i_data[EXT4_IND_BLOCK]), &lb);
                if (retval)
                        goto err_out;
        } else
                lb.curr_block += max_entries;
        if (i_data[EXT4_DIND_BLOCK]) {
                retval = update_dind_extent_range(handle, tmp_inode,
                                le32_to_cpu(i_data[EXT4_DIND_BLOCK]), &lb);
                if (retval)
                        goto err_out;
        } else
                lb.curr_block += max_entries * max_entries;
        if (i_data[EXT4_TIND_BLOCK]) {
                retval = update_tind_extent_range(handle, tmp_inode,
                                le32_to_cpu(i_data[EXT4_TIND_BLOCK]), &lb);
                if (retval)
                        goto err_out;
        }
        /*
         * Build the last extent
         */
        retval = finish_range(handle, tmp_inode, &lb);
err_out:
        if (retval)
                /*
                 * Failure case delete the extent information with the
                 * tmp_inode
                 */
                free_ext_block(handle, tmp_inode);
        else {
                retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
                if (retval)
                        /*
                         * if we fail to swap inode data free the extent
                         * details of the tmp inode
                         */
                        free_ext_block(handle, tmp_inode);
        }

        /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
        retval = ext4_journal_ensure_credits(handle, 1, 0);
        if (retval < 0)
                goto out_stop;
        /*
         * Mark the tmp_inode as of size zero
         */
        i_size_write(tmp_inode, 0);

        /*
         * set the  i_blocks count to zero
         * so that the ext4_evict_inode() does the
         * right job
         *
         * We don't need to take the i_lock because
         * the inode is not visible to user space.
         */
        tmp_inode->i_blocks = 0;
        EXT4_I(tmp_inode)->i_csum_seed = tmp_csum_seed;

        /* Reset the extent details */
        ext4_ext_tree_init(handle, tmp_inode);
out_stop:
        ext4_journal_stop(handle);
out_tmp_inode:
        unlock_new_inode(tmp_inode);
        iput(tmp_inode);
out_unlock:
        ext4_writepages_up_write(inode->i_sb, alloc_ctx);
        return retval;
}

/*
 * Migrate a simple extent-based inode to use the i_blocks[] array
 */
int ext4_ind_migrate(struct inode *inode)
{
        struct ext4_extent_header       *eh;
        struct ext4_sb_info             *sbi = EXT4_SB(inode->i_sb);
        struct ext4_super_block         *es = sbi->s_es;
        struct ext4_inode_info          *ei = EXT4_I(inode);
        struct ext4_extent              *ex;
        unsigned int                    i, len;
        ext4_lblk_t                     start, end;
        ext4_fsblk_t                    blk;
        handle_t                        *handle;
        int                             ret, ret2 = 0;
        int                             alloc_ctx;

        if (!ext4_has_feature_extents(inode->i_sb) ||
            (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                return -EINVAL;

        if (ext4_has_feature_bigalloc(inode->i_sb))
                return -EOPNOTSUPP;

        /*
         * In order to get correct extent info, force all delayed allocation
         * blocks to be allocated, otherwise delayed allocation blocks may not
         * be reflected and bypass the checks on extent header.
         */
        if (test_opt(inode->i_sb, DELALLOC))
                ext4_alloc_da_blocks(inode);

        alloc_ctx = ext4_writepages_down_write(inode->i_sb);

        handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
        if (IS_ERR(handle)) {
                ret = PTR_ERR(handle);
                goto out_unlock;
        }
        /*
         * This operation rewrites the inode's block mapping layout
         * (extents to indirect blocks) and is not tracked in the fast
         * commit log, so disable fast commits for this transaction.
         */
        ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_MIGRATE, handle);

        down_write(&EXT4_I(inode)->i_data_sem);
        ret = ext4_ext_check_inode(inode);
        if (ret)
                goto errout;

        eh = ext_inode_hdr(inode);
        ex  = EXT_FIRST_EXTENT(eh);
        if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
            eh->eh_depth != 0 || le16_to_cpu(eh->eh_entries) > 1) {
                ret = -EOPNOTSUPP;
                goto errout;
        }
        if (eh->eh_entries == 0)
                blk = len = start = end = 0;
        else {
                len = le16_to_cpu(ex->ee_len);
                blk = ext4_ext_pblock(ex);
                start = le32_to_cpu(ex->ee_block);
                end = start + len - 1;
                if (end >= EXT4_NDIR_BLOCKS) {
                        ret = -EOPNOTSUPP;
                        goto errout;
                }
        }

        ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
        memset(ei->i_data, 0, sizeof(ei->i_data));
        for (i = start; i <= end; i++)
                ei->i_data[i] = cpu_to_le32(blk++);
        ret2 = ext4_mark_inode_dirty(handle, inode);
        if (unlikely(ret2 && !ret))
                ret = ret2;
errout:
        up_write(&EXT4_I(inode)->i_data_sem);
        ext4_journal_stop(handle);
out_unlock:
        ext4_writepages_up_write(inode->i_sb, alloc_ctx);
        return ret;
}